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Price 



50 Cts. 







UMTOfiMPHY 






AND 




PRACTICAL ASTRONOMY, 



DESIGNED FOE 



Prepared for the unprepared in Mathematics, enabling them to foretell 
Eclipses, Easters, and the weather by the moon's phases, &c. 



By L. LILLARD. 









KEOKUK: 

REES' JOB OFFICE PRINT 
1866. 





@7"vS>© 





GEOMETRICAL AND ASTRONOMICAL OPERATIONS. 



After a few more issues of the Uranography and Practical 
Astronomy, we will bring out a work of the following title, 
to- wit : " Geometrical and Astronomical Operations, 
designed for Private Students." 

This Work will contain many astronomical cuts, engraved 
expressly for its pages. 

We presume that this book will cost about $1.00. 

L. L. 



E K, IR, .A. T -A.. 



On the 11th page, seventh line from the top, it reads " the 
moon contains one-eighth as much matter as the earth ; " it 
should be one- eightieth. On the 13th page, second line under the 
head of Mars, " its year is thrice as long ;" it should be twice. 
On page 16, near the bottom " 192,080 " should be 192,000. 



URANOGRAPHY 



AND 






PRACTICAL ASTRONOMY, 



DESIGNED FOR 



PRIVATE STUDENTS. 



BY L. LILLARD. 






PRICE FIFTY CENTS: 

ADDRESS L. & J. W. LILLARD, UNION, CLARK COUNTY, MO. 



/ 



KEOKUK : 
Rees' Book: and. Jo"b Office Print, 

1866, 



Entered according to Act of Congress, in the year 1866, by 

L. LILLARD, 

In the Clerk's Office of the District Court of the District of Iowa. 



^ 



> 



PREFACE. 



It has been our design, in the following pages, to compile a work adapted 
to the wants of the rising generation. It may be successfully read by any 
person that has advanced in the common arithmetic as far as proportion, 
and by Uglier mathematical readers. 

We are indebted to Hon. H. N. Robinson for his sound and unsurpassable 
demonstrations, found in his " University Astronomy." 

The Uranography describes the whole Universe, beginning with the 
sun ; then, advancing into the great field of space, step by step, calling upon 
every member of the planetary system, except the asteroids, which are too 
small and numerous to be interesting to our readers. It also describes the 
fixed stars. 

The Practical Astronomy contains rules for calculating the moon's 
phases, eclipses, Easter, &c, &c, too tedious to mention. The Practical 
Astronomy must be studied as a text book ; therefore, the reader need not 
expect to open it, and then apply the rules to the various examples ; but 
must resort to the more elaborate method of study and inspection. 

In hope that this compilation may be found useful, we submit it to the 
public for self-recommendation. 4 

Union, September, 1866. 



TERM S z 



Single Copy $0.50 

Twelve Copies, 5.00 

Twenty-Five Copies, or over, 37)^ cents each. 

All orders should be addressed to 

L. & J. W. LILLARD, 
Union, Clark Co., Mo. 



URANOGRAPHY: 



A DESCRIPTION OF THE UNIVERSE. 



THE SOLAR SYSTEM. 



The Solar System, as at present known, consists of the sun, 
its centre ; eight planets revolving around it, besides about 
eighty- seven asteroids. According to the latest accounts, there 
are twenty moons revolving about these planets, unequally dis- 
tributed among them ; some accompanied with none at all. 
Such is the case with Mercury, Venus and Mars. 



THE SUN. 

The Sun, the great source of light and heat to the planets, is 
the centre of the solar system. It is an immense globe five 
hundred times as large as all the planets put together. Its 
diameter is eight hundred and eighty-three thousand miles. If 
the centre of the sun was placed where the centre of the earth is, 
it would fill the whole orbit of the moon, and reach two hundred 
thousand miles beyond it in all directions. Its volume is nearly 
a million and a half times as great as the earth's, and it contains 
three hundred and fifty-five thousand times as much matter. 



U 11 A N G R A P H Y . 

The sun, viewed through a telescope, looks -like an immense 
globe oi J fire. Its surface., however, is .not always wholly 
luminous. A number of dark spots, surrounded by a lighter 
shadow, are sometimes scattered over the sun's disc, extending 
thirty- five degrees on each side of the solar equator. The 
spots on the sun seem first to have been observed in the 
year 1611, since which time they have constantly attracted 
attention, and have been the subject of investigation among 
astronomers. These spots change their appearance as the sun 
revolves on its axis, and become greater or less, to an observer 
on the earth, as they are turned to or from him; they also 
change in respect to real magnitude and number. One spot, 
seen by Dr. Herschel, was estimated to be more than six times 
the diameter of our earth, being fifty thousand miles in diameter. 
Sometimes forty or fifty of these spots may be seen at the same 
time, and sometimes only one. They are often so large as to be 
seen with the naked eye, which was the case in 1816. In two 
instances these spots have been seen to burst into several parts 
and fly in different directions, like a piece of ice thrown upon the 
floor. In respect to the nature and design of these spots, almost 
every astronomer has formed a different theory. Some have 
supposed them to be solid non-luminous masses of dross, float- 
ing in the liquid fire of the sun ; others, as satelites, revolving 
around him, and hiding his light from us ; others, as immense 
masses, which have fallen on his disc, and are dark colored, be- 
cause they have not yet become sufficiently heated. Dr. Her- 
schel, from many observations with his great telescope, con- 
cludes that the shining matter of the sun consists of a mass of 
phosphoric clouds, and that the spots on his disc are owing to 
disturbances in the equilibrium of this luminous matter, by 
which openings are made through it. But how can these clouds 
give so much heat ? for the hot substance must be the luminous 



U R A N G R A P II Y , 



substance. Therefore, we will investigate the matter after de- 
scribing our earth. 

We will describe the planets in their order from the sun : 



MERCURY. 

Mercury is the nearest planet to the sun. Mercury may be 
seen, at certain times of the year, for a few minutes after sun- 
set or before sunrise, at other times it keeps so close to the sun, 
as to be invisible, being lost in the splendor of the solar beams, 
in the day time, and rising and setting so nearly with the sun, 
gives unfavorable opportunities for observations upon it. Viewed 
through a telescope, it exhibits phases, or changes, just like the 
moon ; this is because we see more of its enlightened part at one 
time than another. The solar heat received at Mercury is nearly 
seven times as great as that of the earth — a temperature more 
than sufficient to make water boil. Mercury's light is also seven 
times as intense as ours, and the sun as seen from this planet 
would appear seven times as large as it does to us. Mercury's 
orbit deviates from a circle much more than that of any other 
planet, the asteroids excepted. This combined with the inclina- 
tion of its axis to the orbit of the planet, produces a great 
variety of seasons and changes of temperature. 
Figure 1. 



Fig. 1 represents the orbit of a planet. S is the sun's 
place nearer one end of the ellipse than the other. 
When the planet arrives at point P it is said to be 
in its perigee, and when at A its apogee. 




8 U R AN GR A P H Y, 

VENUS. 

The second planet from the sun is Venus. On account of its 
nearness it appears larger and more beautiful to us than any 
other member of our planetary system. This planet is so bright 
that it is sometimes visible at midday to the naked eye. During 
part of the year, this planet rises before the sun, and is then 
called morning star. It sets after the sun the balance of the year 
and is then called evening star. Venus is a little smaller than 
the earth. Its diameter has been calculated to be 7,587 miles. 
Venus' light and heat is nearly twice as great as ours. Spots 
have occasionally been seen on the surface of Venus, and moun- 
tains have been observed and estimated to be from fifteen to 
twenty miles high. Venus' phases, when viewed through a tel- 
escope, are similar to those of Mercury and the moon, but it 
never appears exactly full, being invisible at the time when this 
phase would otherwise be seen. At this time the earth, sun 
and Venus are in a straight line, and Venus cannot be seen for 
the splendor of the solar beams. 



THE EARTH. . 

The earth is the third planet in order from the sun. The 
earth is round like a ball, being a little flattened at the polls. 
Its equatorial diameter is 7,925.5 miles, and its polar diameter 
about twenty- six and a half miles less. The circumference of a 
sphere is a little more than three times its diameter ; the distance 
around the earth, therefore, is nearly 25,000 miles. The earth 
is so large that its rotundity is not apparent to a person standing 
on its surface. We know it to be round, however, in several 
ways ; for every one knows the fact, that the earth has been 



URANOGRAPHt.- 9 

many times circumnavigated ; which settles the question. In 
addition to this, any observer may convince himself of this fact; 
for if the observer is on shore, viewing an approaching vessel, 
he sees the topmast first, and from the top, downward, as the 
vessel gradually comes in view. This being the case on every sea, 
and on every portion of the earth, proves that the surface of the 
earth is convex on every part — hence it must be a globe, or nearly 
so. And furthermore, if the earth was a plain, we should see the 
hull as soon as the topmast. The earth makes one revolution on its 
axis in twenty-four hours ; this is called its diurnal motion. 
One half of the earth's surface is constantly receiving the sun's 
light, and the diurnal motion of the earth keeps bringing new 
points into the solar beams, while at the same time withdrawing 
others from the sun's light. The earth nas also an annual motion 
about the sun. Its orbit, like that of other planets, is elliptical, 
but does not deviate much from a circle. Its perihelion is nearly 
3,000,000 miles nearer the sun than its aphelion. The earth's 
orbit is 600,000,000 miles in length, and to get around it in one 
year, the earth must travel over 68,000 miles per hour, or over 
1133 miles per minute. Though we are constantly moving with 
this great velocity, we are unconscious of it. This is because 
we have never known what it is to be at rest ; and again, the 
motion is perfectly easy and regular, there being no obstruction 
in the way. Perhaps we ought to have informed the reader be- 
fore, that at the poles the days are six months long ; when the 
sun is north of the equator, the north pole is illuminated, and 
then it is night at the south pole ; and conversely, when the sun 
is south of the equator, it is day at the south pole, and night at 
the north pole. 

Heat below the earth' } s surface — As we descend below the 
earth's surface, the temperature increases about one degree 
every forty-five feet. At this rate, water would boil at a depth 



10 URANOGRAPHY. 

of less than two miles, and at the depth of one hundred and 
twenty-five miles, all known substances would be melted. It is 
thought, therefore, that the great mass of the interior of the 
earth is in a state of fusion, for the heat is more than two thou- 
sand times sufficient to boil water. The discharge of lava du- 
ring the eruption of volcanoes, goes to prove this ; while the hot 
springs in different parts of the world, show that a high temper- 
ature prevails at no very great depth. At the surface, this inter- 
nal heat is not perceptible, because the outer crust of the earth 
is a bad conductor of heat. Now if the surface of the sun is a 
good conductor of heat, it would allow it to pass through ; and, 
again, if such an immense amount of heat was applied to a good 
conductor, such as iron, it would appear fiery like the sun ; there- 
fore, we may have reasons to believe that this is the case with 
the sun, and that the dark spots on its surface are asteroids fall- 
ing to the sun, and when they disappear, they have become 
heated and are luminous ; for we know no other cause to assign, 
unless the substance that falls on the sun's disc is entirely con- 
sumed. 

It has been stated that the earth is nearer the sun, at one 
period of its revolution, than at another. The change of 
seasons, however, is entirely independent of this fact, and is pro- 
duced by the sun's rays falling on a given point of the earth's 
surface with different degrees of obliquity at different parts of 
its orbit. When the sun is vertical or directly overhead, its heat 
is most intense, and the less its rays deviate from a vertical line, 
in striking the surface, the more heat they impart to it. The 
angle at which the sun's rays strike a given part of the earth's 
surface keeps constantly varying in consequence of the earth's 
revolution in her orbit, with its axis always pointing in one direc- 
tion, or, as it is generally expressed, always parallel to itself. 



URANOGRAPHY. 11 



THE MOON 



The earth is attended by one satellite called the moon — a 
beautiful orb which rules the night with its gentle brilliancy, — 
commander-in-chief of the waters, and sensibly affects the earth'i 
motion. The moon's diameter is 2,165 miles, but its apparent 
size is nearly equal to that of the sun's on account of its near- 
ness to our planet. Its density is but little more than one-half 
that of the earth, and it contains about one-eighth as much 
matter. The moon's mean distance is 240,000 miles from the 
earth, and makes one revolution in its orbit in about twenty-seven 
days and eight hours. From new moon to new moon it requires 
about twenty-nine days and thirteen hours on account of the 
sun's apparent motion from the moon. When any planet or sat- 
ellite is nearest to the body it revolves around, it is said to be in 
perigee, and when farthest, in apogee. We have just used the 
term — sun's apparent motion — because the sun does really ap- 
pear to move, instead of the earth. But this is not so ; the 
earth revolves around the sun, as it has been previously stated. 
The moon revolves on its axis in exactly the same time it takes 
it to revolve round the earth, and in the same direction. 
This is the most wonderful observed fact that has ever been seen 
in our infinite extended universe. This coincidence seems al- 
most impossible according to the laws of astronomy as discovered 
by Kepler, which will ljgreafter be investigated for the reader to 
crack his skull on, and to solve some very nice astronomical 
problems. The moon is non-luminous and shines only by the 
reflected light of the sun ; hence, the half sphere presented to 
the sun is bright, while the opposite one is dark. The sun, moon 
and earth are constantly taking different positions in respect to 
each other, and the illuminated portion is changing also. 



12 URANGGRAPHY. 

Hence, arises^, what are called the moon's phases. When new, 
the moon lies between the earth and sun, near a line connecting 
their centres. Her dark side is then toward us and she is in- 
visible, but very soon we see her in the west, a little, after sunset, 
with a beautiful crescent on the side next to the sun. Every 
night we find the crescent still growing larger and larger, and, 
finally, she is seen ninety degrees west of the sun ; half her disc 
i3 then illuminated. She is then said to be in her first quarter, 
but her crescent or illuminated part, still increases, until she ar- 
rives at a point where the earth, sun and moon are again in a 
straight line or nearly so ; but this time the earth is in the mid- 
dle, therefore, we are on the same side of the moon as the sun 
is, and the enlightened side being always next to the sun, it is 
visible to us, and is called full moon. When she advances 
ninety degrees beyond full she reaches her third quarter. Then 
she presents the same amount of luminated surface as she did in 
the first quarter, but this -time the east side of the moon is visible. 
She advances still farther, until she finally presents her dark 
side to us again ; after this she will go through the same phases, 
as she makes another revolution in her orbit. As seen from the 
moon, the earth presents the same phases that the moon does to us, 
but in reverse order. When we have new moon, the moon has 
full earth — 'a splendid orb, thirteen times as large as the full 
moon. When she is in her first quarter, the earth is in her third 
quarter, &c. Most of the writers say that the moon has no at- 
mosphere; hence, it must be destitute of water, for any liquid on 
its surface would long since have been evaporated by the heat of 
the lunar days. Viewed through a telescope, the surface appears 
very rough, covered with deep valleys and lofty mountains, 
several of which are from three to four miles high, and their 
shadows have been seen to extend across the rugged plains. Sev- 
eral of the ancient astronomers thought they could discover vol- 



URANOGRAPHY. 13 

canoes in a state of eruption, with their great telescopes ; but the 
latest accounts say that the supposed volcanoes are superior re- 
flective substances. The great telescope of the Earl oe Rosse 
shows plainly every object on the lunar surface that is one hun- 
dred feet high, but shows no signs of life or habitation. 



MARS. 

Mars, the fourth planet from the sun, is 4,546 miles in di- 
ameter. Its day is a little longer than ours, and its year about 
thrice as long. About every other year, when it comes to the 
meridian, near midnight, it is then most conspicuous, and the 
next year it is scarcely noticed by the common observer. This 
may seem rather strange to the reader, but we will see if we can- 
not simplify it. The distance from the sun to Mars is about one 
hundred and forty-four millions of miles and the' earth being about 
ninety-five millions of miles from the sun ; when Mars is on the 
same side of the sun that the earth is, the distance from us to 
Mars equals 144,000,000—95,000,000=49,000,000 ; hence, our 
distance from Mars at this time is only forty-nine millions of 
miles. One more year finds our-earth in the same position, and, 
as it takes Mars two years to make a revolution, by this time she 
has only made half a revolution. Therefore, Mars is on the op- 
posite side of the sun from the earth, and her distance from the- 
earth is equal to 144,000,000 -f 95 5 000,000 = 239,000,000, 
which is nearly five times her distance one year previous, and it 
is evident that she would appear smaller. The apparent sizes of 
the other planets do not change like that of Mars because their 
relative change in distance is not so great. (Venus is an excep- 
tion to this, her farthest distance is about six times her less.) 
The physical appearance of Mars is somewhat remarkable. His 



14 URANOSRAPHY. 

polar regions, when seen through a telescope, have a brilliancy 
so much greater than the rest of his disc, that there can be little 
doubt, that, as with the earth, so with this planet, accumulations 
of ice or snow take place during the winters of those, regions. 
In 1781, the south polar spot was extremely bright ; for a year 
it had not been exposed to the solar heat. The color of the 
planet most probably arises from a dense atmosphere which sur- 
rounds him, of the existence of which there is other proof, de- 
pending on the appearance of stars as they approach him ; they 
grow dim and are sometimes wholly extinguished as their rays 
pass through that medium. Mars is easily distinguished in the 
heavens by his red, fiery appearance. 



JUPITER. 

The next planet, as known to ancient astronomers, is Jupiter ; 
but its distance is so great beyond the orbit of Mars, that the 
vast field of space between the two was considered as an imper- 
fection, and it was thought among astronomers that a planet 
ought to occupy that vacant space. The discovery of Bodi's 
law encouraged the belief among the astronomers that there was 
once a planet between Mars and Jupiter. It is as follows, if we 
take the series of numbers as below : 

0, 3, 6, 12, 24, 48, 96, 192, &c, and then add the number 4 
to each, and we have 4, 7, 10, 16, 28, 52, 100, 196, &c, &c. 
This last series of numbers very nearly corresponds to the rela- 
tive distances o£ the planets from the sun, with the exception of 
the number 28. Itvras this trivial number 28 that introduced 
the subject of investigating the theory of explosion, combined 
with the many asteroids afterwards discovered in this vacant field 
©f space, of which the 87th has been lately discovered by Prof. 



URAN06RAPHY. 15 

N. R. Pogson, of the Royal Observatory, Madras, Hence, ft 
was the general impression among astronomers, that there was 
once a planet revolving around the sun in this field of space, and 
from some cause or other it exploded, sending fragments in 
many directions. It does seem strange that there are so many 
small worlds., and their orbits so near together, were they not 
formerly one body. Now, if these little worlds were scattered 
from Mercury to Neptune, no such thought would have penetrated 
the minds of the astronomers. 

Jupiter is the largest planet in the solar system, being nearly 
one thousand three hundred times as large as our earth. Its 
revolution around the earth is performed in about twelve years, 
and it only takes this great globe ten hours to make one revolu- 
tion around its axis. It revolves with such great velocity that 
every point on its equator must turn four hundred and fifty miles 
per minute. So great is the centrifugal force at the equator 
that its poles are flattened very much. The disc of Jupiter is 
always crossed, in an eastern and western direction, by dark 
bands. These belts are not alike at all times ; they vary in 
breadth and in situation, but never in their direction. They have 
even been seen broken up and distributed over the whole face of 
the planet, but this vision is extremely rare. When Jupiter is 
viewed with a telescope, even of moderate power, it is seen 
accompanied by four small stars, nearly in a straight line paral- 
lel to the ecliptic. These always accompany the planet, and are 
called its satellites or moons. They are always changing their 
position with respect to one another and to the planet, being 
sometimes all to the left, and somtimes all to the right ; but 
generally some on each side. These moons are not all the same 
distance from the planet, and they are thus distinguished : that 
being called the first, which is nearest to the planet ; the next 
nearest is called the second, and so on. Galileo discovered the 



16 UKAKOSBAPHT. 

the satellites of Jupiter in 1610. Sometimes a satellite passes 
between the sun and Jupiter, and casts a shadow which describes 
a chord across the disc of the planet. This produces an eclipse 
of the sun, to Jupiter similar to those which the moon produces 
on the earth, which shows that Jupiter and his moons are non- 
luminous bodies, shining by the reflected light of the sun. The 
motions of Jupiter's moons are from west to east, just the same 
way as the earth's moon. 

The velocity of light was discovered by the eclipses of Jupi- 
ter's satellites, which we illustrate thus : 

Figure 2. 




Let S (Fig. 2) represent the sun, J Jupiter, E earth and M Jupiter's first 
satellite. Now this satellite passes through Jupiter's shadow every revolu- 
tion it makes around the plarjet. Suppose the earth is at the point A when 
M is seen entering Jupiter's shadow. Now E is moving m the direction 
indicated by the arrow, which, as it is shown, is at right angles towards 
Jupiter. In 42h, 28m and 35s, M is again seen entering the shadow ; by 
this time E has arrived at the point B, about the same distance from J, as 
the earth when it was at point A, as is seen by the figure. Therefore, it is 
42h, 28m and 35s from one eclipse to another. Now if we renew the 
observation : When E is moving from C to D, toward J, the time between 
the eclipses will be shortened fifteen seconds, on account of the earth advan- 
cing on meeting the light ; and during this time the earth has moved in its 
orbit 2,880,000 miles ; this divided by fifteen, will give 192,080 miles for the 
velocity of light per second. 



URANOGRAPHV. 17 

All of Jupiter's satellites are larger than our moon, except one, 
and three of them are eclipsed every lunation, yea, totally 
eclipsed ; and the fourth is very often eclipsed. The relation 
between the orbits and motions are such that for many years to 
come, Jupiter will never be deprived of the light of all her moons 
at the same time. 



S ATURN. 

The next planet in order of remoteness from the sun, is 
Saturn, the most wonderful object in the solar system. This 
world, though less than Jupiter, is about 79,800 miles in diame- 
ter, and one thousand times greater than our earth. This great 
globe is attended by eight satellites or moons, and is surrounded 
by two broad, flat and extremely thin rings ; both lying in one 
plane, and separated by a very narrow space, and from the planet 
by a much wider. 

The dimensions are as follows : 

Miles. 

Exterior diameter of exterior rings 176,418 

Interior do do 155,272 

Exterior diameter of interior ring 151,690 

Interior do do 117,339 

Equatorial diameter of the planet 79,160 

Interval between the planet and interior ring 19,090 

Interval of the rings 1,791 

Thickness of the rings 100 

The body of Saturn is striped, similar to that of Jupiter, and 
the planet and rings are known to be opaque, by the shadows 
they cast upon each other ; which may be seen by the aid of a 
telescope. The diameter of Saturn's largest moon is about 
3,247 miles. The rings reflect light to the planet, and are a very 
good substitute for a moon ; these rings are said to be solid masses 
revolving with great rapidity around the planet, therefore, the 
c 



18 URANOGRAPHY. 

centrifugal force balances the attraction of .the planet, and keeps 
them from falling in on the disc of the body. These rings 
revolve around the planet in the surprisingly short period of ten 
hours, twenty-nine minutes and seventeen seconds ; hence, every 
point on the exterior circumference of the exterior ring, must 
turn eight hundred and eighty miles per minute. Saturn's day 
is not half so long as ours, but it is twenty-nine and half of our 
years in making one complete revolution in its orbit. 



URANUS . 

The next planet beyond Saturn is Uranus. It was discovered 
by Sir W. F. Herschel in the year 1781. Uranus is rarely to 
be seen, without a telescope ; yet, under f axorable circum- 
stances, it may be, as a star of the sixth magnitude.* Its 
real diameter is about 35,000 miles, or, about eighty times 
the size of our earth ; and it takes it eighty- four years to 
make one revolution around the sun. Uranus is attended 
by six moons, which move from East to West, contrary 
to the motions of other moons, and nearly perpendicular to the 
orbit of the planet. Uranus is eighty times the magnitude of 
the earth. 



NEPTUNE . 

Neptune, the most remote planet of the solar system, is invis- 
ible to the naked eye. We have no account of the surface of the 
planet, but its diameter is 39,800 miles, which is about one hun- 
dred and twenty-five times as large as our earth. Neptune per- 
forms its revolution around the sun in about one hundred and 



*The visible stars are divided into six classes. The brighter are of the 
first magnitude, and those just visible are of the sixth. 



URAN06RAPHT. 19 

sixty-five years. It has one moon which is about 250,000 miles 
from the planet. Neptune was discovered in the year 1846 by 
two astronomers, both of Europe. However strange, both astron- 
omers told the distance from the sun, the size and time of revo- 
lution of the planet Neptune around the sun without ever seeing 
it ; and even went so far as to assign its position in the heavens, 
at a given date. As the historian says, it was on the 13th of 
September, that the results of these calculations reached Dr. 
Galle, of Berlin, and that very evening he searched the pre- 
dicted point with his large telescope. The inquiry was, is it 
there ? Yes, it is there. These calculations were made by com- 
paring observations on the perturbations of Uranus. We will 
give practical exercises on this in the Practical Astronomy which 
will explain the proposition. 

We will now give the reader a comparative representation of 
the solar system : 

" Choose any well leveled field or bowling green. On it place 
a globe two feet in diameter ; this will represent the sun ; Mer- 
cury will be represented by a grain of mustard seed, on the cir- 
cumference of a circle of 1 64 feet in diameter, for its orbit. Venus 
a pea, on a circle 284 feet in diameter ; the earth also, a pea, on 
a circle of 430 feet; Mars a rather large sized pinhead, on a circle 
of 654 feet ; Juno, Ceres, &c, &c, grains of sand, in orbits of 
from 800 to 1500 feet ; Jupiter a moderate sized orange, in a 
circle nearly half a mile across , Saturn a small orange, on a 
circle of four- fifths of a mile ; and Uranus a full sized cherry, or 
small plum, upon the circumference of a circle more than a mile 
and a half in diameter. As to getting correct notions on this 
subject by drawing circles on paper, or, still worse, from those 
very childish toys called orreries, it is out of the question. To 
imitate the motions of the planets in the above mentioned orbits, 
Mercury must describe its own diameter in 41 seconds ; Venus ? 



20 U 11 A N G R A P H Y . 

in 4 minutes and 14 seconds ; the earth, in 7 minutes ; Mars, in 
4 minutes, 48 seconds ; Jupiter, in 2 hours, 56 minutes ; Saturn, 
in 3 hours, 13 minutes ; and Uranus, in 2 hours, 16 minutes. — « 
HerscheV s Jlstronomy. 



COMETS. 

Besides the planets, satellites and asteroids, there are great 
numbers of other bodies, which gradually appear, increasing in 
brightness and velocity, until they reach their perihelion, and as 
gradually diminish, pass off and are lost in the distance ; these 
are called comets. From their physical appearance, especially 
of their long luminous tails, they were for a long time objects of 
terror to mankind, and were regarded with superstitious terror as 
precursors of war, famine and other pestilences. It has only 
been about sixty years since these fears were banished by a 
knowledge of the rarity of comets ; and being now better under- 
stood, excite only the curiosity of the people in general. Hon. 
H. N. Robinson says : It is further to be observed that the tails 
of comets begin to appear, as the bodies approach the sun ; their 
length increases with this proximity, and they do not acquire 
their greatest extent, until after passing the perihelion. The 
direction is generally opposite to the sun, forming a curve slightly 
concave, the sun on the concave side. The portion of the comet 
nearest to the sun a must move more rapidly than its remoter 
parts, and this will account for the lengthening of the tail. The 
tail is, however, -by no means an invariable appendage of comets. 
Many of the brightest have been observed to have short and feeble 
tails, and not a few have been entire without them. On the 
other hand, instances are not wanting of comets furnished with 
many tails, or streams of diverging light. That of 1744 had no 
less than six, spread out like an immense fan, extending to a 



URANOGRAPHY. 21 

distance of nearly thirty degrees in length. The smaller comets, 
such as are visible only in telescopes, and far the most nu- 
merous, offer frequently no appearance of a tail, and appear only 
as round or somewhat oval vaporous masses, more dense toward 
the center ; where, however, they appear to have no distinct nu- 
cleus, or anything which seems entitled to be considered as a 
solid body. The tail of the comet of 1456, was sixty degrees 
long. That of 1618, one hundred degrees, so that its tail had 
not all risen when its head reached the middle of the heavens. 
The comet of 1680 was so great, that though its head set soon 
after the sun, its tail, seventy degrees long, continued visible all 
night. The comet of 1689, had a tail sixty- eight degrees long. 
That of 1769, had a tail more than ninety degrees in length. 
That of 1811, had a tail twenty-three degrees long. The recent 
comet of 1843, had a tail sixty degrees in length. 

Comets, in passing among and near the planets, are materially 
drawn aside from their courses, and in some cases have their 
orbits entirely changed. This is remarkably the case with Jupi- 
ter, which seems, by some strange fatality, to be constantly in 
their way, and to serve as a perpetual stumbling block to them. 
In the case of the remarkable comet of 1770, which was found 
by Lexell to revolve in a moderate ellipse in the period of about 
five years, and whose return was predicted by him accordingly — 
the prediction was disappointed by the comet actually getting en- 
tangled among the satellites of Jupiter, and being completely 
thrown out of its orbit by the attraction of that planet, and 
forced into a much larger ellipse. By this extraordinary rencoun- 
ter, the motion of the satellites suffered not the least perceptible 
derangement, which is a sufficient proof of the smallness of the 
comet's mass. — Robinson s Astronomy, 

The following are part of the elements of the orbits of the 
three comets, which have appeared according to prediction, taken 
from the work of Professor Littrow. 



22 URANOGRAPHY. 

Halley. Encke, Biela, 

Major axis of orbit, that of the 

earth being called 1, 18. 2.2 3.6 

Minor axis. ' 4.6 1.2 2.4. 

Time of revolution, in years, 76. 3.29 * 6.74 

Time of the perihelion passage, Nov. 16, 1835. May 6, 1832. Nov. 27, 1832 

About one hundred and twenty comets have been foretold, but 
this is nothing compared with the whole number, that visit our 
solar system, which is estimated by some to be about. 7,000,000, 
and by others to be about 28,000,000. But we can say that we 
are ignorant of the number, for all such calculations must surely 
be guess work. It is said that in 1454, the moon was eclipsed 
by a comet. This undoubtedly was very alarming, for the comet 
was less than 240,000 miles from the earth, and its rarity was 
not understood at this time. Professor Kendall, in his Uranog- 
raphy, speaking of the fears occasioned by comets, says : "An- 
other source of apprehension, with regard to comets, arises from 
the possibility of their striking our earth. It is quite probable 
that even in the historical period the earth has been enveloped in 
the tail of a comet. It is not likely that the effect would be 
sensible at the time. The actual shock of the head of a comet 
against the earth is extremely improbable. It is not likely to 
happen once in a million of years. 

If such a shock should occur, the consequences might perhaps 
be very trivial. It is quite possible that many of the comets are 
not heavier than a single mountain on the surface of the earth. 
It is well known that the size of mountains on the earth is illus- 
trated by comparing them to particles of dust in a common globe. 



FIXED STARS . 

The fixed stars are so called, because they maintain the same 
position relatively to each other. For example, you see the 



U K A N U K A P II Y . 23 

seven stars forming the same dipper they did years ago. The 
number of fixed stars is unknown. The telescope reveals mil- 
lions ; however, great the magnifying power, it brings stars into 
the field of view that are just discernible. The fixed stars are 
divided into twenty magnitudes, according to their brightness ; 
the first six are visible to the naked eye ; the rest are called tel- 
escopic stars, because seen only with the telescope. There are 
about twenty-four stars of the first magnitude, fifty of the sec- 
ond and two hundred of the third ; but the number in the other 
classes increases so rapidly as to be beyond enumeration. The 
fixed stars are suns, occupying the centre of a system, probably, 
similar to ours. They are supposed to be of different sizes, and 
situated at different distances from the sun. The distance to the 
fixed stars is so great that if the sun filled the whole orbit of the 
earth it would be invisible from them. It is said that the recent 
improvements in telescopes have enabled astronomers to compute 
the distance of nine of the nearest stars. It is shown in the 
preceding pages that light flies 192,000 miles in one second, but it 
would take it fourteen years to fly from the star Sirus to us, and 
from the Pole star it would take forty- eight years ; and it is 
conjectured that the magnifying power of the great telescopes 
will penetrate 363,294,720,000,000,000 miles into the field of 
space, a distance that light could not traverse in less than sixty 
thousand years.* The mind is lost in comprehending such a 
mighty distance. The Milky Way, is a broad belt of apparent 
vaporous light, extending from the pole in the north to the hori- 
zon in the south. The stars are so thick in this zone of light 
that their rays are blended together, which is the cause of it 
appearing like a cloud of vapor. 

Dr. Herschel saw, in the course of a quarter of an hour, the 



*If all the stars would explode at this time, some of them would be seen 
in their present position for more than sixty thousand years. 



24 URANOSRAPHY. 

astonishing number of 116,000 stars pass through the field of 
view, when he directed his powerful telescope to this almost end- 
less zone of light. Although they appear so thick, they must 
be at least 9,500,000,000,000 miles apart, which is 100,000 
times the radius of the earth's orbit ; and it is calculated that 
their diameters cannot fall short of 200,000,000 miles. 



MEASURING THE DISTANCE TO THE SUN. 



We shall now give the reader an idea how the distance to the sun 
is told. If a globe, say ten feet in diameter, be placed just before 
your eyes, it will obscure all of the sight, but as it is rolled 
away from you, its apparent size grows smaller and smaller as 
the distance increases. Hence, to every apparent size there is a 
corresponding distance, and if we know the increase in distance 
corresponding to the decrease in the apparent size, we may 
assign its position at any time ; but this is a geometrical prob- 
lem, and will have to be omitted in a work like this. Upon 
this principle all distances are told without measuring. 



AEE THE CELESTIAL WORLDS INHABITED ? 



We close the Uranography by asking a question that has never 



URANOGRAPHY. 25 

been answered. Are the celestial worlds inhabited? We ask 
this question, but cannot answer it ; nor will it be answered 
until there is a great improvement made in telescopes. All that 
we can say upon this subject, is, that we believe all of the planets 
are inhabited. We know that one is — the earth — and from 
the similar appearance of the other planets, it is natural to sup- 
pose that they are also inhabited. Nothing seems to be created 
without an object, and it would appear very strange if the earth 
were the only We peopled by intelligent creatures. If we 
inhabited Jupiter, our weight might overcome our strength and 
make us helpless ; but who can doubt that the Great Creator, 
who has adopted us to our globe, could as easily adopt creatures 
to others. 



PRACTICAL ASTRONOMY. 



REMARKS 



The following astronomical calculations are approximate, but sufficiently 
accurate to meet the wants of the reader. The results of the calculations of 
the moon's phases, eclipses, &c, are within five or six minutes of the true 
time, and often much nearer. The time of the moon's entrance into its 
apogee and perigee, may be predicted to the nearest hour ; and we believe 
that the rest of the calculations are very accurate. 



PRACTICAL ASTRONOMY 



MOON'S PHASES 



The phases of the moon have been explained in the Urano- 
graphy ; and we shall now attempt to calculate them by the fol- 
lowing tables, hoping that the reader will readily understand us ; 
although, we will not explain how these tables were made, 
because it would take a mathematician to understand it. All 
tabular calculations are made from Greenwich mean time. 

To Find the JVew Moons in any Given Year. — 
From table I. take out the given year and the whole horizon- 
tal line headed as above. The second column shows the mean 
time of the first new moon in the year, reckoned from the begin- 
ing of the same year. The columns headed I. , II. , ITT. and 
IV., correct the mean, and give the apparent time of new 
moon. If we want the second new moon we must add one luna- 
tion and the whole horizontal line taken from table II.; the 
heading of which corresponds to the first. If the third new 
moon is required, we must add two lunations. (The first col- 
umn in table II. , shows the number of lunations.) And when 
this is done, add up each column separately. But if there are 
more than four figures under columns I. or II., drop the last 
figure in adding ; and if more than two under columns III. or IV. , 



30 



PRACTICAL ASTRONOMY. 



also drop the last figure in adding. And then with sum under 
column I. enter table III., and with its nearest equivalent, found 
in a column headed Arg. ; take out the corresponding equation 
from column I., and place it in the column of days, hours and 
minutes. Then proceed in the same manner with the numbers 
under columns II. , III. and TV". , and again add up ;he column of 
days,, hours and minutes, which will be the apparent Greenwich 
time, reckoned from the beginning of the year. Now subtract 
from the number of days, the greatest number that can be sub- 
tracted, taken from table IV. , if it is a common year, take the 
number to be substracted from column headed Com., otherwise 
from column headed Leap. The remainder will be the day of the 
the corresponding month. 



TABLE I. 





MEAN NEW MOONS AND ARGUMENTS IN JANUARY. 




1 


MEAN N. 


MOON 


IN JAN. 


i. 


ii. ! 


in. 


IV. 


1 * 


A. D. 


D. 


H. 


M. 












1861 


10 


9 


22 


0290 


2840 


31 


25 


995 


1862 


29 


6 


55 


0800 


2163 


30 


14 


102 


1863 


18- 


15 


44 


0504 


0769 


13 


03 


125 


1864 l 


8 





32 


0204 


9374 


96 


92 


147 


1865 


25 


22 


5 


0714 


8698 


94 


80 


256 


1866 


15 


6 


53 


0416 


7303 


77 


69 


277 


1867 


4 


15 


42 


0118 


5909 


60 


58 


299 


1868 h 


23 


13 


14 


0628 


5231 


59 


46 


407 


1869 


11 


22 


3 


0330 


3837 


42 


35 


429 


1870 


1 


6 


51 


0032 


2442 


25 


24 


451 


1871 


20 


4 


24 


0542 


1765 


23 


12 


559 


1872 L 


8 


13 


13 


0244 


0371 


05 


01 


581 


1873 


27 


10 


46 


0754 


9694 


03 


89 


689 


1874 


17 


19 


35 


0456 


8300 


86 


78 


711 


1875 


7 


4 


24 


0158 


6906 


69 


67 


733 


1876 L 


26 


1 


57 


0668 


6229 


67 


55 


841 


1877 


14 


10 


49 


0370 


4835 


50 


44 


863 


1878 


3 


18 


38 


0072 


3441 


33 


23 


885 


1879 


22 


6 


11 


0582 


2764 


31 


21 


993 


1880 L 


11 


15 





0280 


1370 


14 


10 


015 


1881 


















1882 



















0^7" The letter L is affixed to the Leap years ii> the first column. 



PRACTICAL ASTRONOMY. 



31 



TABLE II. 

MEAN LUNATIONS AND CHANGES OF ARGUMENTS. 



NO. 




LUNATION. 




i. 1 


ii. | 


in. 


IV. | 


N. 




D. 


H. 


M. 












1-128 





05 


32 


0006 


0084 


01 


01 


001 


1-64 





11 


4 


0012 


0167 


02 


02 


001 


1-32 





22 


9 


0025 


0335 


04 


03 


003 


1-16 


1 


20 


18 


0050 


0670 


07 


06 


005 


1-12 


2 


11 


4 


0068 


0893 


09 


08 


007 


1-8 


3 


16 


35 


0101 


1339 


14 


12 


on 


1-6 


4 


22 


7 


0135 


1786 


19 


17 


014 


1-4 


7 


9 


11 


0202 


2679 


29 


25 


022 


1-2 


14 


18 


22 


0404 


5359 


58 


50 


043 


1 


29 


12 


44 


0808 


0717 


15 


99 


085 


2 


59 


1 


28 


1617 


1434 


31 


98 


170 


3 


88 


14 


12 


2425 


2151 


46 


97 


256 


4 


118 


2 


56 


3234 


2869 


61 


96 


341 


5 


147 


15 


40 


4042 


3586 


76 


95 


425 


6 


177 


4 


24 


4851 


4303 


92 


95 


511 


7 


206 


17 


8 


5659 


5020 


07 


94 


596 


8 


236 


5 


52 


6468 


5737 


22 


93 


682 


9 


265 


18 


36 


7276 


6454 


37 


92 


767 


10 


295 


7 


20 


8085 


7171 


53 


91 


852 


11 


324 


20 


5 


8893 


7889 


68 


90 


937 


12 


354 


8 


49 


• 9702 


8606 


83 


89 


022 


13 


383 


21 


33 


0510 


9323 


98 


88 


108 



32 



PRACTICAL ASTRONOMY, 



TABLE III. 







EQUATIONS FOR ARGUMENTS I. 


AND II. 






AEG. | 


i. 


1 


ii. 




ARGK 




I- 1 


ii. 






H. 


M. 


H. 


M. 




H. 


M. 


H. 


M. 


0000 


4 


20 


10 


10 


5000 


4 


20 


10 


10 


0100 


4 


36 


9 


36 


5100 


4 


05 


10 


50 


0200 


4 


52 


9 


2 


5200 


3 


49 


11 


30 


0300 


5 


8 


8 


28 


5300 


3 


34 


12 


9 


0400 


5 


24 


7 


55 


5400 


3 


19 


12 


48 


0500 


5 


40 


7 


22 


5500 


3 


4 


13 


26 


0600 


5 


55 


6 


49 


5600 


2 


49 


14 


3 


0700 


6 


10 


6 


17 


5700 


2 


35 


14 


39 


0800 


6 


24 


5 


46 


5800 


2 


21 


15 


13 


0900 


6 


38 


5 


15 


5900 


2 


8 


15 


46 


1000 


6 


51 


4 


46 


6000 


1 


55 


16 


18 


1100 


7 


4 


4 


17 


6100 


1 


42 


16 


48 


1200 


7 


15 


3 


50 


6200 


1 


31 


17 


16 


1300 


7 


27 


3 


24 


6300 


1 


19 


17 


42 


1400 


7 


37 


2 


59 


6400 


1 


9 


18 


6 


1500 


7 


47 


2 


35 


6500 





59 


18 


28 


1600 


7 


55 


2 


14 


6600 





50 


18 


48 


1700 


8 


03 


1 


53 


6700 





42 


19 


6 


1800 


8 


10 


1 


35 


6800 





34 


19 


21 


1900 


8 


16 


1 


18 


6900 





28 


19 


33 


2000 


8 


21 


1 


03 


7000 





22 


19 


44 


2100 


8 


25 





51 


7100 





17 


19 


52 


2200 


8 


29 





40 


7200 





14 


19 


57 


2300 


8 


31 





32 


7300 





11 


20 





2400 


8 


32 





25 


7400 





9 


20 


1 


2500 


8 


32 





21 


7500 





8 


19 


59 


2600 


8 


31 





19 


7600 





8 


19 


55 


2700 


8 


29 





20 


7700 





9 


19 


48 


2800 


8 


26 





23 


7800 





11 


19 


40 


2900 


8 


23 





28 


7900 





15 


19 


29 


3000 


8 


18 





36 


8000 





19 


19 


17 


3100 


8 


12 





47 


8100 





24 


19 


2 


3200 


8 


6 





59 


8200 





30 


18 


45 


3300 


7 


58 


1 


14 


8300 





37 


18 


27 


3400 


7 


50 


1 


32 


8400 





45 


18 


6 


3500 


7 


41 


1 


52 


8500 





53 


17 


45 


3600 


7 


31 


2 


14 


8600 


1 


3 


17 


21 


3700 


7 


21 


2 


38 


8700 


1 


13 


16 


66 


3800 


7 


9 


3 


04 


8800 


1 


25 


16 


30 


3900 


6 


58 


3 


32 


8900 


1 


36 


16 


3 


4000 


6 


45 


4 


2 


9000 


1 


49 


15 


34 


4100 


6 


32 


4 


34 


9100 


2 


2 


15 


5 


4200 


6 


19 


5 


7 


9200 


2 


16 


14 


34 


4300 


6 


5 


5 


41 


9300 


2 


30 


14 


3 


4400 


5 


51 


6 


17 


9400 


2 


45 


13 


31 


4500 


5 


36 


6 


54 


9500 


3 





12 


58 


4600 


5 


21 


7 


32 


9600 


3 


16 


12 


25 


4700 


5 


6 


8 


11 


9700 


3 


32 


11 


52 


4800 


4 


51 


8 


50 


9800 


3 


48 


11 


18 


4900 


4 


35 


9 


30 


9900 


4 


4 


10 


44 



PRACTICAL ASTRONOMY 



33 



TABLE II I.— Continued. 



EQUATIONS FOR ARGUMENTS in. AND IV. 



6 
3 


in. 


IV. 


< 


in. 


IV. 


< 


in. 


IV. 


£5 


in. 


IV. 




M. 


M. 




M. 


M. 


M. 


M. 




M. 


M. 


00 


10 


20 


25 


3 


31 


50 


10 


20 


75 


17 


9 


01 


10 


21 


26 


3 


31 


51 


10 


19 


76 


17 


9 


02 


9 


21 


27 


3 


30 


52 


11 


19 


77 


17 


10 


03 


9 


22 


28 


3 


30 


53 


11 


18 


78 


17 


10 


04 


8 


23 


29 


3 


30 


54 


12 


17 


79 


17 


10 


05 


8 


23 


30 


3 


30 


55 


12 


17 


80 


17 


10 


06 


7 


24 


31 


3 


30 


56 


13 


16 


81 


17 


10 


07 


7 


25 


32 


4 


29 


57 


13 


15 


82 


16 


10 


08 


7 


25 


33 


4 


29 


58 


13 


15 


83 


16 


11 


09 


6 


26 


34 


4 


29 


59 


14 


14 


84 


16 


11 


10 


6 


26 


35 


4 


29 


60 


14 


14 


85 


16 


11 


11 


5 


27 


36 


5 


28 


61 


15 


13 


86 


15 


12 


12 


5 


27 


37 


5 


28 


62 


15 


13 


87 


15 


12 


13 


5 


28 


38 


5 


27 


63 


15 


12 


88 


15 


13 


ii- 


5 


28 


39 


5 


27 


64 


15 


12 


89 


15 


13 


is 


4 


29 


40 


6 


26 


65 


16 


11 


90 


14 


14 


16 


4 


29 


41 


6 


26 


66 


16 


11 


91 


14 


14 


17 


4 


29 


42 


7 


25 


67 


16 


11 


92 


13 


15 


18 


4 


29 


43 


7 


25 


68 


16 


10 


93 


13 


15 


19 


3 


30 


44 


7 


24 


69 


17 


10 


94 


13 


16 


20 


3 


30 


45 


8 


23 


70 


17 


10 


95 


12 


17 


21 


o 


30 


46 


8 


23 


71 


17 


10 


96 


12 


17 


22 


3 


30 


47 


9 


22 


72 


17 


10 


97 


11 


18 


23 


3 


30 


48 


9 


21 


73 


17 


10 


98 


11 


19 


21 


3 


31 


49 


10 


21 


74 


17 


9 


99 


10 


19 



TABLE IV. 

NUMBER OF DAYS FROM THE COMMENCEMENT OF THE YEAR TO THE 
FIRST OF EACH MONTH. 



MONTHS. 



January.. 
February 
March . . , 

April 

May 

June..,.. 

B 



COM. 


LEAP. 








31 


31 


59 


60 


90 


91 


120 


121 


151 


152 



MONTHS. 



July 

August... . 
September, 
October.. . 
November. 
December 



COM. 



181 
212 
243 
273 
304 
334 



LEAP. 



182 
213 
244 
274 
305 
335 



34 



PRACTICAL ASTRONOMY. 



EXAMPLES. 

1. Required the time of new moon in January, 1866, Green- 
wich apparent time. 

Bring down the whole horizontal line corresponding to the 
year 1866, found in table L: 







MEAN 


NEW 


MOON 


I i. 


| ii. 


in. 


1 iv. 


N. 




D. 


H. 


M. 




1 








1866 


15 


6 


53 


0416 


1 7303 


77 


69 


277 




15 


6 


53 


| 0416 


| 7303 


77 


| 69 


' 277 


I. 




5 


27 












II. 




20 


00 












III. 






17 












IV. 






10 













January 16 08 47 

Now with the number, 0416, enter column Arg., in Table III ; 
and take from its corresponding column I. the hours and 
minutes corresponding to the number ; but its nearest equivalent 
is 0400, and the equation 5 hours and 24 minutes. Now, while 
the number is increasing from 0400 to 0500, the equation 
increases from 5 hours and 24 minutes to 5 hours and 40 minutes ; 
and, by proportion, we find that while the argument is increasing 
from 0400 to 0416, the equation increases 2.56 minntes, which, 
added to 5 hours, 24 minutes, gives 5 hours, 26.56 minutes for 
the equation corresponding to the number 0416 ; but the 
equations are always added to the time column to their nearest 
minute ; therefore, we will add 5 hours and 27 minutes. We may 
proceed in the same manner with the arguments, 7303, 77 and 69, 
always taking the equations from columns headed the same as 
their arguments. After the equations are all added to the time 
of mean new moon, we have, new moon, January, 16 days, 8 
hours and 47 minutes, Greenwich apparent time. As Greenwich 
is east of the United States, it is later in the day there than in 
this country. And if we substract the difference of time between 
Greenwich and any point in the United States, we will have the 
time corresponding to that point- For this purpose we inser 



PRACTICAL ASTRONOMY. 



35 



Table V. For instance, if we want the time of new moon at 
Washington, D. C, all we have to do is, to subtract the differ- 
ence of time as shown by Table V., which is 5 hours and 8 
minutes, subtracted from Greenwich time of new moon, leaves 16 
days, 3 hours and 89 minutes, for Washington time of new moon. 



TABLE V. 



SHOWING THE DIFFERENCE OF TIME BETWEEN GREENWICH AND CITIES, ETC. 
IN THE UNITED STATES AND CANADAS. 



TOWJNS. 



Augusta, Maine 

Portland, " 

Concord, New Hampshire.. 

Montpelier, Vermont 

Boston, Massachusetts . . . 

Northampton, Mass 

Newport, Rhode Island 

Hartford, Connecticut 

New York, N. Y 

Syracuse, New York 

Buffalo, " " 

Trenton, New Jersey 

Philadelphia, Penna 

Harrisburg, " 

Pittsburg, " 

Dover, Delaware 

Baltimore, Maryland 

Washington, D. C 

Richmond, Virginia 

Natural Bridge, Va 

Washington, N. C 

Baleigb, N. C 

Salisbury, N. C 

Charleston, S. C 

Columbia, S. C 

Savannah, Georgia 

Columbus, " 

Suwanee River, Florida 

Milton, x " 

Montgomery, Alabama 

Mobile, " 

Jackson, Mississippi 

Natchez, " 

Nashville, Tennessee 

Memphis, " 

Little Rock, Ark 

New Orleans, Louisiana . . . 
Shrevesport, " 



Difference 
of Time. 



TOWNS. 



Difference 
of Time. 



H. M. 

4 40 Galveston, Texas. 

4 41 Austin, 

4 46 Cleveland, Ohio 

4 50 Cincinnati, " 

4 44 ; Columbus, " * 

4 50 Frankfort, Kentucky . 

4 45 Mammoth Cave, Ky. 

4 50 Bowling Green, Ky . . 

4 56 Shelby ville, Indiana. . 

5 5 Indianapolis, " 
5 16 ; Terre Haute. " 

4 59 Chicago, Illinois ..... 

5 1 ^oria, i( 

5 7 ! Rock Island," 

5 20 j Alton, " 

5 2 ! Quincy, " 

5 6 St. Louis, Missouri . . 

5 8 Pilot Knob, " 

5 10 Palmyra, " • .. 

5 18 JeffersonCity " 

5 8 St. Joseph, " 

5 14 Davenport, Iowa.... 

5 22 Keokuk, " .... 

5 20 Des Moines, " .... 

5 24 j Madison, Wisconsin,. 

5 25 | Milwaukee " .... 

5 40 Pictured Rocks, Mich 

5 33 Detroit, 

5 49 San Diego, California. 

5 46 j San Francisco, Cal . . . 

5 53; Monterey, Mexico .. . 

6 01! Quebec, Canada .. 

6 6 Stanstead, " 

5 47 St. Johns, " 

6 1 Montreal, " 

6 10 Toronto, " 

6 Paris, " 

6 16 



M. 

20 
31 

27 

38 

32 

39 

43 

45 

42 

44 

50 

51 

58 

2 

1 

6 

1 

3 

6 

9 

20 

2 

6 

15 

57 

52 

44 

32 

49 

10 

8 

45 

49 

53 

54 

17 

21 



36 



PRACTICAL ASTRONOMY. 



Note. — Time, as calculated by the Tables, is astronomical time, and is 
counted from noon till noon, and from one to twenty-four hours. Therefore, 
the astronomical day commences at the middle of the civil day, and is by 
this cause twelve hours behind it. Then, if we add I2h. to the astronomical 
day it will reduce it to a civil one, reckoned from midnight to midnight, and 
from one to twenty-fours. From 1 to 12 corresponds to A. M., and from 
12 to 24 to P. M. 

2. Required the time of the third new moon in 1866, corres- 
ponding to Greenwich, Boston, and Cincinnati astronomical and 
civil time. 



1866 
2 Lun. 



MEAN NEW MOON. 



D. H. M. 

15 6 53 

59 1 28 





74 


8 


21 


I. 


8 


22 


II. 


16 


49 


III. 




7 


IV 






11 



0416 
1617 



ii,. 



7303 
1434 



2033 8737 



in. 



77 
31 



OS 



IV. 



69 
98 



67 



N. 



277 
170 



447 



75 
Table IV. 59 



50 



March 16 9 50 
New moon, Greenwich Astronomical time, March . 
Boston difference of time (Table V.) 



16d. 9h. 50m. 
4 44 



New moon, Boston astronomical time 16 5 06 

In the same manner, we find new moon, Cincinnati, astro- 
nomical time 16 4 12 

Following instructions in the preceding note we have : 

Greenwich civil time 16d. 9h. 50m. p. m. 

Boston, " " 16 5 06 " 

Cincinnati " " , 16 4 12 " 

0^7" After this, astronomical time will be meant, when other time is not 
mentioned. 



3. Required the sixth new moon, in 1868, civil time, for 
Washington, D. C. 



PRACTICAL ASTRONOMY. 



3T 





MEAN NEW MOON. 


i. 


ii. 


in. 


IV. 


N. 


1868 l. 
5 Luna. 


D. H. M. 

23 13 14 
147 15 40 


0628 
4042 


5231 
3586 


59 
76 


46 
95 


407 

425 




171 4 54 


4670 


8817 


35 


41 


832 



I. 

II. 

III. 

IV. 



5 

16 



11 

25 

4 

26 



172 
Table IV. l. 152 



00 



June 20 



00 



Greenwich time, June 20d. 3h. 00m, 

Washington difference of time .' 5 8 



Washington time 20d. 21h. 52m 

Adding 12 hours, we have Washington civil time, 2 Id. 8h. 52m. A. M, 



EQUATION OF TIME 



The Sun gives apparent time, and there must be another cor- 
rection applied to give the true time as shown by a perfect clock. 
It is called the equation of time, and is from two causes. 

1st. The unequal apparent motion of the Sun along the 
Ecliptic. 

2d. The variable inclination of this motion to the 
Equator. 

The true time corresponds with apparent time, four days in 
every year ; or in other words, the four days in the year on which 
the sun and clock agree, are April 15th, June 16th, September 
1st, and December 24th. Table VI. shows the equation of time 



38 



PRACTICAL ASTRONOMY 



for every fifth, day of the year. The equations to be added to 
apparent time, are placed in column headed Add, and vice 



versa. 



TABLE VI. 



SHOWING THE EQUATION OF TIME FOR EVERY FIFTH DAY IN THE YEAR. 



Day of 


Add. 


Sub- 


Day of 


Add. 


Sob- 


Day of 


Add. 


Sob- 


Month. 


tract. 


W ONTH. 


tract. 


Month. 


tract. 




M. 


M. 




M. 


M. 




m. 


m. 


Jan .... 5 


6 




May... 5 




3 


Sept. .. 2 




1 


" 10 


8 




" ...10 




4 


" 


..'.'■■ 7 




2 


" ....15 


10 




" ...15 




4 


it 


...12 




4 


" ....20 


11 




" ...20 




4 


a ■ 


...17 




6 


" ....25 


13 




"•■ ...25 




3 


a 


...22 




7 


" ....30 


14 




" ...30 




3 


" 


...29 




10 


Feb. ... 4 


14 




j June . . 4 




2 


Oct. 


... 4 




11 


" . ... 9 


14 




" ... 9 




1 


" . 


... 9 




13 


" 14 


14 




« ...14 







a 


...14 




11 


" 19 


14 




" ...19 


1 




" . 


...19 




15 


" 24 


13 




" ...24 


2 




(< 


...24 




16 


March . . 1 


13 




" ...29 


3 




a 


...29 




16 


" ..6 


11 




July ... 4 


4 




Nov. 


... 3 




16 


" ..11 


10 




" ... 9 


5 




" 


... 8 




16 


" ..16 


9 




" ...14 


6 




(t . 


...13 




16 


" ..21 


7 




" ... 19 


6 




" 


...18 




15 


" ..26 


6 




» ...24 


6 




it 


...23 




13 


" ..31 


4 




" ...29 


6 




" 


...28 




12 


April. . . 5 


3 




Aug. ... 3 


6 




Bee. 


... 3 




10 


" ..10 


1 




" ... 8 


5 




a 


...8 




8 


" ..15 







" ... 13 


5 




a 


...13 




5 


" ..20 




1 


" ...18 


4 




cc 


...18 




3 


11 ..25 




2 


" ...23 


2 




a 


...23 




1 


" ..30 




3 


" ...28 


1 




11 . 


...28 


2 





EXAMPLES. 



1. Required the equation of time for Nov. 8th, and how must 
it be applied. 

We find by the Table, that the equation for the 8th, is 16m., 
and following up the column, we find that it is headed, sub- 
tract, therefore, it must be subtracted. 



PRACTICAL ASTRONOMY. 



89 



2. Required the equation of time for April 15th, and how 
must it be applied, Answer — 00m., therefore, it needn't be 
applied at all. 

3. Required the equation of time for Jan. 12th. Answer — 
9m. to be added. 

4. Required the true civil time of the tenth new moon in 1870. 
for Keokuk, Iowa. 







MEAN NEW MOON. 


r ' 


ii. 


in. 


IV. 


N, 


1870. 
-Luna. 
9 Luna. 


D. 
T 

265 


H. 

6 

18 


M. 

51 

36 


0032 
7276 


2442 
6454 


25 

37 


24 
92 


451 

767 


I. 

IT. 

III. 

IV. 


267 


1 

1 

16 


27 
19 
2 
15 
29 


7308 


8896 


63 
/ 


16 


218 


Table IV 

September 

Keokuk diff. Time. 

Keokuk Time .... 
Note, p. 36 


267 
243 


19 


33 




24 


19 
6 


33 
6 


• 


24 


13 
12 


27 





01 



27 



Apparent Civil .... 25 

Equation of time. . . 8 

Keokuk true civil time, September, 25d\, lh., 19m. a. m. 



FIRST QUARTER, FULL MOON, AND LAST QUARTER. 

As 1 lunation means one revolution, K, K, and K lunation 
would equal one-fourth, one-half, and three-fourths of a revo- 
lution. Therefore, if we add M lunation to new moon, we will 
have first quarter, and if we add % lunation, we will have full 
moon ; and by adding % lunation we get third quarter. 



40 



PRACTICAL ASTRONOMY 



EXAMPLES. 



1. Required the moon's first quarter after the first new moon, 
in 1866, Greenwich time. 







MEAN NEW MOON. 


i. 


ii. 


in. 


IV. 


N. 


1866. 
% Luna. 


D. H. M. 

15 6 53 
7 9 11 


0416 
0202 


7303 
2679 


77 
29 


69 
25 


277 
022 


I. 

II. 
III. 
IY. 


22 16 04 

5 57 

10 17 

7 

16 


0618 


9982 


06 


94 


299 



Aws.,Jan. 23 8 



41 



2. Required the time of the first full moon after the fourth 
new moon, in 1867; New York time. 





MEAN NEW MOON. 


I. 


ii. 


in. 


IV. 


N. 




D. 


H. M. 












1867. 


4 


15 42 


0118 


5509 


60 


58 


299 


3 Luna. 


88 


14 12 


2425 


2151 


46 


97 


256 


i^ Luna. 


14 


18 22 


0404 


5359 


58 


50 


43 




108 


00 16 


2947 


3419 


64 


05 


598 


I. 


8 21 












II. 


1 36 












III. 


15 












IV. 




23 












108 


10 51 




N.Y.diff.time 




4 56 












108 


5 55 




Table IV. 


90 















Ans., April, 18 5 55 

3. Required the first third quarter after the same new moon, 
New York time. 



PRACTICAL ASTRONOMY 



41 





MEAN NEW MOON. 


i. 


ii. 


in. 


IV. 


N. 


1867. 
3 Luna. 
*% Luna 


D. H. M. 

4 15 42 
88 14 12 
22 3 33 


0118 

2425 
0606 


5909 
2151 

8038 


60 

46 
87 


58 
97 
75 


299 

256 

65 




115 9 27 


3149 


6098 | 


93 


30 


620 



I. 

II. 

III. 

IV. 



Table IV. 

April, 
N.Y. diff. time. 



8 9 

16 48 

13 

30 



116 

90 


11 07 


26 


11 07 
4 56 



Ans,, April, 26 6 11 

*% Luna, is obtained by adding ^ and % of a lunation together. 



THE WEATHER 



The Weather is said to be governed by the time that the 
moon enters its quarters ; therefore, the Weather is different East 
and West of us, and the same kind of Weather that we have here 
extends from the North to the South Pole. If it is true that the 
Weather is govorneed by the moon, by the table prepared for 
predicting the Weather, we find that if it is raining in New York 
the cloud must extend from the North to the South Pole, and 
that part of the earth's surface to be rained on must be in the 
shape of a lune, whose width must be 60 degrees. Hence, we 
consider all predictions of the Weather guess-work, and believe 
the following rule is the best that can be scared up : 



42 



PRACTICAL ASTRONOMY. 



TABLE VII. 

FOR FORETELLING THE WEATHER. 



If the New Moon, the First 

Quarter, the Full Moon, 
or the Last Quarter happens 



Between midnight and) 
2 in the morning . . . ) 

Bet. 2 and 4, morning. 
" 4 and 6. " 
" 6 and 8, " 



8 and 10, 
10 and 12, 



In Stmmer. 



Fair 1 

Cold, frequent Showers . . 

Rain 

Wind and Rain 



In Winter. 



" Noon and 
'•' 2 and 
" 4 and 



P.M. 



6 and 8 " 

8 and 10 " 
10 and midnight 



Changeable 

Frequent Showers. ... 

Very Rainy 

Changeable 

Fair 

Fair, if Wind K-W. 
Raining if South or 
S.-W 

Ditto 

Fair 



Hard Frost, unless the 
wind be South or West 

Snow and Stormy. 

Rain. 

Stormy. 

Cold Rain, if wind be W., 
Snow if E. 

Cold, and High Winds.. 

Snow or Rain 

Fair and Mild. 

Fair. 

Fair and Frosty, if Wind 
N". or K-E., Rain or 
Snow, if S. or S.-W. 

Ditto. 

Fair and Frosty. 



In addition to Table VII., we may divide the moon's orbit into 
twelve equal parts, and find the time of its entrance into each 
division, by adding one-twelfth lunation at a time. In calcu- 
lating the moon's phases, if the sun, under column N, is very 
near 250, the Weather will be a little drier than as indicated by 
the Table. If very near 750, a little drier. 

By following the above instructions, the reader may be able to 
tell whether the following year will be a good crop-year or not. 

Observations. — The nearer the time of the moon's entrance 
to noon or midnight, the more nearly will the result occur with 
the prediction. It is also said that the less dependence is to be 
placed on the Table in Winter than Summer. 

1. Required the Weather following the phases previously cal- 
culated. It must be remembered that all astronomical time must 
be reduced to true civil time before predicting. Answer. 

2. Required the Weather following the new moon in August, 
1866, for Missouri. Answer—Changeable. 



PRACTICAL ASTRONOMY. 43 

3. Required the Weather following the last quarter in August, 
1866, for Missouri. Answer — Changeable. 

4. Required the Weather following the first quarter, in January, 
1866, for Virginia; which will answer for all States due North 
and South. Answer — Fair and mild. 



CHRONOLOGICAL 



To Find the Day of the Week Corresponding to any 
Day of any Month. — Subtract 1 from the given year, add one- 
fourth of itself, rejecting the remainder ; and then add the num- 
ber of days from the beginning of the year, plus the day of the 
month. Now divide by 7. (the number of days in the week) 
and the remainder will show the day of the week. 

If the remainder is 0, it will be Sunday. 
If the remainder is 1, it will be Monday. 
If the remainder is 2, it will be Tuesday. 
If the remainder is 3, it will be Wednesday. 
If the remainder is 4, it will be Thursday. 
If the remainder is 5, it will be Friday. • 
If the remainder is 6, it will be Saturday. 

EXAMPLES. 

1. Required the day of the week corresponding to the 4th of 

July, 1866. 

Given Year 1866 

Substract 1 

Leaves 1865 

Adding one-fourth . . 466 

Gives 2331 

July, Table I Y 18 1 

Add day of the Month 4 

Sum. 2516-^-7=359, and 3 for the remainder. 

It has just been stated that, if the remainder is 3, it will be 

Wednesday. Answer — Wednesday. 



44 PRACTICAL ASTRONOMY. 

2. What day of the week will the 7th of August be in the 
year 1880 ? Answer — Saturday. 

3. What day did the year 1700 begin on ? Answer — 
Wednesday. 

EASTER. 

Easter, a festival of the Christian Church, observed in mem- 
ory of our Saviour's resurrection. 

In the primitive ages of the Church, there were very great 
disputes about the particular time when this festival was' to be 
held. The Asiatic Churches held their Easter upon the very 
same day the Jews observed their Passover ; and others on the 
first Sunday after the first full moon in the new year. 

This controversy was determined in the council of Nice, when 
it was ordained that Easter should be held upon one and the 
same day, which should always be a Sunday in all Christian 
Churches throughout the world. 

But though the Christian Churches differed as to the time of 
celebrating Easter, yet they all agreed in showing particular re- 
spect and honor to this festival. It was distinguished by the 
ancient writers by the name of dominica gaudily that is, Sun- 
day of joy. On this day prisoners and slaves were set free, 
and the poor liberally provided for. The eve or vigil of this 
festival was celebrated with more than ordinary parade, which 
continued till midnight — it being a tradition of the Church that 
our Saviour rose a little after midnight — but. in the East, the 
vigil lasted till cock-crowing. It was in conformity to the cus- 
tom of the Jews in celebrating their Passover on the fourteenth 
day of the first month ; but the following rule was finally estab- 
lished by the world : 

RULE. 

By the Tables, find the first full moon after the 20th of 
March — the following Sunday will be Easter-day. 



PRACTICAL ASTRONOMY. 



45 



The first full moon after the 20th of March is always the third 
■or fourth in the year, and if we know its date, we can tell the 
date of the next Sunday (Easter-day). 

EXAMPLES. 

1. Required Easter-day for 1867. 





MEAN N. MOON. 


i. 


ii. 


in. 


IV. 


N. 


1867. 
~% Luna. 
3 Luna. 


D. H. M. 

4 15 42 

14 18 22 
88 14 12 


0118 

0404 

2425 


5909 
5359 
2151 


60 

58 
46 


58 
50 
97 


299 
043 
256 


I. 


108 00 16 
8 21 


2947 


3419 


• 64 


05 


598 



II. 
III. 

IV. 



36 
15 

23 



108 
Table IV.. 90 



10 51 



April 18 10 51 

Civil time, l?d., 10h., 51m. n Full moon, Thursday, three 
more days gives Sunday. To April 18th, add three — April 21st 
— for Easter- day. 

2. Required Easter-day for 1868. Answer — April 12th. 

EASTER SUNDAYS. 



1869 -March 28th. 

1871 

1873 April 13th. 

1875 March 28th. 



1870 April 17th. 

1872 March 24th. 

1874 April 5th. 

1876- March 26th. 



PERIGEE, APOGEE, & c 



The words Perigee, Apogee, Perihelion, and Aphelion, are 
derived from the Greek language, and have the following mean- 
ing : 



46 



PRACTICAL ASTltONOMY. 



Perigee, near the Planet ; Apogee, from the Planet ; Peri- 
helion, near the Sun ; Aphelion, from the Sun. 

It is evident that the moon's apparent size is greatest when 
the moon is nearest the Earth, or in Perigee, and least when in 
Apogee. Therefore, if we can find its apparent semi- diameter, 
at any time, we can also tell when it enters Apogee and Perigee. 



TABLE VIII. 

SHOWING THE MOON'S SEMI-DIAMETER. 



ARG. II. 


MOON'S S. D. 


ARG. II. 


ARG. II. 


MOON'S S. D. 


ARG. II. 


0000 


]6 29 


0300 


2750 


15 23 


7250 


0250 


16 26 


9750 


3000 


15 16 


7000 


0500 


16 25 


9500 


3250 


15 10 


6750 


0750 


16 21 


9250 


3500 


15 7 


6500 


1000 


16 17 


9000 


3750 


15 3 


6250 


1250 


16 11 


8750 


4000 


14 56 


6000 


1500 


16 3 


8500 


4250 


14 54 


5750 


1750 


15 56 


8250 


4500 


14 50 


5500 


2000 


15 50 


8000 


4750 


14 48 


5250 


2250 


15 42 


7750 


5000 


14 45 


5000 


2500 


15 31 


7500 









When calculating the moon's phases, we may also calculate 
its apparent size. . With the sum under column headed II., enter 
Table VIII., and find its nearest equivalent in column headed 
II., and the corresponding number in column S. D. will be the 
moon's semi- diameter. When the moon's S. D. is at the top of 
the column, it is in Perigee, and when at the bottom, in Apogee. 
Hence, we may write the following rule : 

RULE. 

1st. Add to new moon that part of a lunation that will bring 
column II. to 0000 (or nearly so), which will give the time that 
the moon enters its Perigee. 

2d. Add to new moon that part of a lunation that will bring 
column II. to 5000 (or nearly so), which will give the time that 
the moon enters its Apogee. 



PRACTICAL ASTRONOMY 



47 



EXAMPLES. 

1. Required the time of the moon's first entrance into its 
Perigee after the first new moon in January, 1866. 





MEAK 


N. MOON. 


i. 


ii. 


in. 


IV. 


N. 




D. 


H. M. 












1866. 


15 


6 53 


0416 


7303 


77 


69 


277 


% Luna. 


7 


9 11 


0202 


2679 


29 


25 


022 


l-5l2th " 





1 23 


0002 


0021 


00 


00 


OGO 




22 


17 27 


0620 


0003 


06 


94 


299 


I. 




5 58 












II. 




10 10 












III. 




7 












IV. 




16 













Answer— Jan. 23 9 58— Greenwich Time. 

Note. — 1-5 12th Lunation is found by dividing 1 Lunation by 512. 

2. Required the time it will be in its iipogee after the same 



new moo 


n. 


















MEAN 


NEW MOON. 


I. 


ir. 


in. 


IV. 


N. 




D. 


H. 


M. 












1866 


15 


6 


53 


0416 


7309 


77 


69 


277 


1-2 Luna. 


14 


18 


22 


0404 


5359 


58 


50 


043 


7-32 " 


6 


11 


2 


0177 


2344 


25 


22 


19 




36 


12 


17 


0997 


5012 


60 


41 


339 


1 




6 


50 












II 




10 


14 












III 






14 












IV 






26 














37 


6 


01 




Table IS 


r. 31 

















Ans., Feb. 6 



01 — Greenwich Time. 



O^T 7-32 Lunation may be obtained by multiplying 1 Lunation by 7, 
and then divide by 32. 

By inspecting the common almanac, we find that the moon was 
in Perigee, January 28d, and in Apogee February 6th. 



ECLIPSES 



When the light of a heavenly body or the body itself is ob- 
scured, it is said to be eclipsed. There are two kinds of Eclipses 
— first, a heavenly body may be eclipsed by the interposition of 
another heavenly body; second, an opaque body may be eclipsed 
by the shadow of another opaque body. Of all the Eclipses, the 
Eclipses of the Sun and Moon are the most important. An 
Eclipse of the sun is caused by the moon's getting between it 
and the earth, and intercepting its rays. This can happen only 
at new moon, because, when between us and the sun, the moon 
must present to us her unenlightened side. 

The Eclipse of the moon is caused by the earth's getting be- 
tween it and the sun. This can take place only at full moon, 
because when the earth is between the sun and the moon the latter 
must present her enlightened side to the earth. 

An Eclipse is called total, when the whole disc is obscured ; 
and partial, when only a portion is obscured. When the whole 
disc of the sun is obscured, except a narrow ring around the outer 
edge, it is called an annular Eclipse, from the Latin word 
annulus, a ring. 

The greatest number of Eclipses that can happen in a year, is 
seven ; the least number, two ; but there are generally four. 

If the moon's path coincided with the sun's, there would be an 
Eclipse of the sun at every new moon, and an Eclipse of the 
moon at every full moon ; but it does not coincide, it inclines to 
it by an angle of 5 deg. and 8 min., crossing the sun's path at 
two opposite points. 

The moon's orbit is divided into 1,000 equal parts, beginning 
at that point where the moon crosses the ecliptic in coming North, 



PRACTICAL ASTRONOMY. 49 

•which is called its ascending node ; and the descending node 
would be represented by 500. If the moon is at or near either 
of these points when it is new or full, there is an Eclipse. 
Column N, when calculating new or full moon, shows the position 
of the moon in respect to its nodes. If there are more than 
three figures in the sum of column N, drop the last one in adding. 

RULE FIRST — TO FIND THE ECLIPSES OF THE SUN. 

Add to the first new moon a sufficient number of luna- 
tions to bring column JV within 37 of 500, 000, or 1,000 — 
the corresponding time of new moon will be the time of 
Eclipse at greatest obscuration. 

If N is less than 37 or 500, the Eclipse will be risible in the 
Northern Hemisphere; or, if N is less than 1,000 or greater 
than 500, the Eclipse will be visible in the Southern Hemisphere. 

The amount of Eclipse corresponding to the different points 
on the earth, belongs to the high mathematics, and must be ex- 
cluded in a work like this. 

If the moon's distance from either node is greater than 37, 
and less than 53, ihere may be an Eclipse, but it is doubtful : 
we shall have to omit all doubtful cases, for their removal would 
require many minor problems caused by the irregular action of 
the sun on the moon. 

Eclipses are either partial, annular, or total. All Eclipses of 
the sun that happen within 25 of either node, are either annular 
or total, and may be predicted in the following manner: 

Table IX. shows the semi- diameter of the sun for every tenth 
day of the year, and by Table VIH. we can find the semi- 
diameter of the moon. Now if the semi-diameter of the moon 
is greater than the sun's, the Eclipse will be total, otherwise, it 
will be annular, as seen from some parts of the earth. 



50 



PRACTICAL ASTRONOMY. 



TABLE IX. 



BUN'S SEMI-DIAMETER FOR EVERY TENTH DAY OF TEE YEAR. 



DAYS. 


JANUARY. 


APRIL. 


JULY. 


OCTOBER. 




MIN. SEC. 


MIN. SEC. 


MIN. SEC. 


MIN. SEC. 


1 


16 18 


16 1 


15 46 


.16 1 


11 


16 17 


15 58 


15 46 


16 3 


21 


16 17 


15 55 


15 46 


16 7 




FEBRUARY. 


MAY. 


AUGUST. 


NOVEMBER. 


1 


16 15 


15 53 


15 47 


• 16 9 


11 


16 13 


15 51 


15 49 


16 12 


21 


16 11 


15 49 


15 51 


16 14 




MAECH. 


JUNE. 


SEPTEMBER. 


DECEMBER. 


1 


16 10 


15 48 


15 53 


• 16 16 


11 


16 7 


15 46 


15 56 


16 17 


21 


16 4 


15 46 


15 58 


16 18 



EXAMPLES. 

Required an Eclipse of the sun for 1867. 





MEAN NEW MOON. 


i. 


ii. 


in. 


IV. 


N. 


1867. 
2 Luna. 


D. H. M. 

4 15 42- 
59 1 28 


0118 
1617 


5909 
1434 


60 
31 


58 

98 


299 
170 




63 17 10 


1735 


7343 


91 


56 


469 



I. 

II. 

III. 

IV. 



Table IV. 
Ans.. March 



20 



6 



14 

16 



64 
59 



12 46 



5 21 46 — Greenwich Time. 

Column N shows that there must be an Eclipse of the sun 
visible in the Northern Hemisphere. 

The result shows Greenwich time, which may be reduced to 
civil time corresponding to any point in the United States. It 
must be remembered, that if a Solar Eclipse happens in the night 
at any place, it will be invisible to that place. As N is tolerably 
near the limits of a Solar Eclipse, the Eclipse must be visible to 
the Northern part of the Eastern Hemisphere. 

The following is a catalogue of the Solar Eclipses that will be 
visible in New England and New York, between the years 1865 
and 1900 ; the dates are given in civil time : 



PRACTICAL ASTRONOMY. 51 

1865, October 19th. Digits eclipsed, 8K, on sun's Southern 
limb. 

1866, October 8th. K digit eclipsed. South of New York no 
eclipse. 

1869, August 7th. Digits eclipsed, 10, in sun's Southern limb. 

This eclipse will be total in North Carolina, Kentucky, Illi- 
nois, &c. 

1873, May 25th. Sun rises eclipsed at Boston. 

1875, September 29th. This eclipse will be annular in Maine, 
New Hampshire, and Vermont. 

1876, March 25th. Eclipse on sun's Northern limb. 

1878, July 29th. Two-thirds of the sun's disc will be obscured. 

Eclipse on sun's Southern limb. 
1880, December 31st. Sun rises eclipsed. One-half of the 

sun's disc will be obscured. 

1885, March 16th. 6K digits eclipsed on sun's Northern limb. 

1886, August 28th. Sun's Southern limb eclipsed. 

1892, October 20th. Two-thirds of the sun is to be darkened. 

1897, July 29th. Eclipse on sun's Southern limb. 

1900, May 28th. 11 digits eclipsed on sun's southern limb. 

This eclipse will be total in Virginia. 

RULE SECOND— TO FIND THE ECLIPSES OP THE MOON. 

Add to the first full moon a sufficient number of luna- 
tions to bring column JY within 25 of 500, 000, or 1,000 — 
the corresponding time of full moon will be the time of 
eclipse at greatest obscuration. 

If N is less than 25 or 500, the eclipse will be on the south 
edge of the moon. Or, if N is less than 1,000, or greater than 
500, the eclipse will be on the moon's northern limb. 

If the moon's distance from either node is greater than 
25, and less than 35, there may be an eclipse, but it is doubtful. 
If N is within 10 of either node, the eclipse will be total, other- 
wise partial. 

EXAMPLE. 

Required an eclipse of the moon for 1867. 



52 



PRACTICAL ASTRONOMY. 





MEAN N. MOON. 


i. 


ii. 


in. 


IV. 


N. 




D. 


H. 


M. 












1867. 


4 


15 


42 


0118 


5909 


60 


58 


299 


% Luna. 


14 


18 


22 


0404 


5359 


58 


50 


43 


2 Luna. 


59 


1 


28 


1617 


1434 


31 


98 


170 




78 


11 


32 


2139 


2702 


49 


06 


512 


I. 


8 


27 












II. 





20 












III. 




10 












IV. 






24 












78 


20 


63 




Table IV.. 


59 

















Arts., March 19 20 53 — Greenwich Time. 

We may reduce the above to civil time corresponding to any 
point ; and if the sun is down, the eclipse will be visible at that 
point. 



KEPLER'S LAWS 



1. The orbits of the planets are ellipses, of which the 
sun occupies one of the focuses. 

2. The radius vector in each case describes equal areas 
in equal times. 

3. The squares of the times of revolution are to each 
other as the cubes of the mean distances from the Sun. 

The first of these is a mere fact drawn from observations. 
The second is also an observed fact — but will admit of an ex- 
planation, by Geometry combined with the law of inertia. 

The third may be demonstrated by the Calculus — and by 
geometrical proportion, if we consider the orbits circular, (which 
is not far from the truth), 

Table X. is a tabular view of the Solar System, (with tha 
asteroids excluded). By applying Kepler's laws, we can find 
the time of revolution corresponding to any distance. 



PRACTICAL ASTRONOMY. 



53 



TABLE X. 

TABULAR VIEW OF THE SOLAR SYSTEM. 





Diameter? 


Names. 


in miles 


Sun. . 


883,000 


Merc . 


3,224 


Venus 


7,689 


Earth. 


7,916 


Mars . 


4,398 


Jupt. . 


89,170 


Saturn 


79/140 


Uran . 


35,100 


Kept . 


39,800 


Moon. 


2,160 





Time of 




, 




Distance fom '.Ir 
sun in miles. 


revMut'ii 
r o u n d 


Siderial 
rotation. 


and 


Bulk. 




the sun. 










Days. 


D. H. 

25 12 




1,380,0(0 


37,000,000 


88 


24 5 


7 


1-15 


68,000,000 


225 


23 21 


2 


8-9 


91000,000 


365 


24 


1 


i 


144,000,000 


68 r i 


24 39 


X. 


7-24 


480,000,000 


4,33; 


9 56 


1-26 


1,300 


900,000,000 


10.759 


10 29 


1-100 


1,00* 


1,800,000,000 


30,687 


9 30 


1-330 


8C 


2,850,000,000 


60,128 


Unknown 


1-799 


125 


95,000,000 


365 


27 7% 


1 


1-49 



Gravity 



28.19 

1.22 

0.96 
1.00 
0.50 
2.70 
1.25 
1.06 



veloc 
ityper 
min. 
la 
miles. 



1833 
1400 
1133 
900 
500 
366 
250 



38 



JUPITER'S SATELLITES. 


SATURN'S SATELLITES. 


Sat. 


Dist from 
Jupiter. 


lime of revolution 
round Jupiter. 


'Sat. 


Dist. from 
Saturn. 


Time of revolution 
round Saturn. 


I 

II 
III 
IY 


Miles. 
264,490 
420,815 
671,234 

1,180,582 


D. H. M. 

1 18 28 

3 14 58 

7 3 42 

16 16 32 


I 

11 

III 

IV 

V 

VI 

VII 

VIII 


Miles. 
199,627 
153,496 
190,044 
243,449 

788,258 
2,297,541 
Not well 


D. H. M. 

22 37 

1 8 53 

1 21 18 

2 17 44 
4 12 25 

15 22 41 


SATELLITES OF URANUS. 


Sat. 


Dist from 
Uranus. 


Time of revolution 
round Uranus. 


79 7 54 
known. 




Miles. 
224,155 

290,821 
339,052 
388,718 
777,481 
1,555,872 


D. H. M. 

5 21 25 

8 16 57 

10 23 4 

13 10 56 

38 1 48 

107 16 42 


NEPTUNE'S SATELLITES. 


I 

II 
III 
IV 

V 
VI 


Sat 


Dist. from\ Time of revolution 
Neptune. \ round Neptune. 

I 


I 


Miles. 
240,000 





EXAMPLES. 

1. Required the time of revolution of a supposed planet 
whose distance is 200,000.000 miles from the sun. 

2 2 3 3 

365 days : (Answer) : : 95 : 200. 

•Answer. 

Kepler's laws can also be applied to secondary planets. 

2. How far is Saturn's Vth moon from the planet. 

Answer. 



54 PRACTICAL ASTRONOMY. 

Now let us suppose that the planet Neptune is unknown — we 
find hj observations that it disturbs its neighboring planets in 
the same point of the heavens every 165 years, therefore, its 
time of revolution round the sun is 165 years ; and by Kepler's 
laws we can find its distance from the centre of motion. The 
planet Neptune was thus discovered by Le Verrier and Adams. 



MISCELLANEOUS. 



The following is a list of all the transits of Mercury that will 

occur between the years 1866 and 1900 : 

1868 Nov. 4 

1878... May 6 

1881 Nov. 7 

1891 May 9 

1894 Nov. 10 

Venus will cross the sun's disc in the year 1874, Dec. 8th, 
and again in the year 1882, Dec. 6th. 

The following problems require astronomical resolution : A, 
in latitude 30 degrees, (immaterial whether North or South) 
rises with the sun. on the 20th of March, and follows his shadow 
all day — where is he at night, provided he travels three miles 
per hour? Answer — 11.7 miles towards the nearest pole. 

B, in latitude 00 degrees, rises with the sun on the 22d of 
September, and follows his shadow all day — where is he at night, 
provided he walks at a certain rate all day ? 

Answer — At the point where he started. 

fgj" The two preceding examples may be omitted by all that are not 
acquainted with Mathematical Astronomy. 

To Produce Table I. — Add a sufficient number of lunations 

to the last horizontal line in Table I., to carry the time column 

to the first of January of the next year. Every time we do this 

we increase the Table one year ; therefore, we may produce it 

indefinitely. 



PRACTICAL ASTRONO 



55 



EXAMPLE. 

Increase Table I. two years. 





MEAN 


NEW MOON. 


i. 


II. 


in. 


IV. 


N. 


1880 L 
13 Luna. 


D. 
11 

383 


H. M. 
15 

21 33 


0284 
0510 


1370 
9323 


14 
93 


10 

88 


015 
108 




395 
366 


12 33 


0794 


0693 


07 


98 


123 


1881 


29 


12 33 


0794 


0693 


07 


98 


123 



To the last horizontal line, add TrLunations, and from the 
sum, subtract the number of days in the year 1880, then we have 
the Table increased one year. In the same manner the reader 
may keep on increasing it. 



VOCABULARY OF ASTRONOMICAL TERMS. 



Acceleration — An increase in the rapidity of the motion of a 
moving body. 

Air — A transparent, invisible, elastic fluid, in which we move 
and breathe. 

Altitude — The height of an objoct. 

Amplitude — The angular distance from the East or West, 
measured on the horizon. 

Angle — The opening between two lines that meet. 

Angular Distance — The opening of two lines drawn from a 
given point to two distant objects. 

Annular — Having the form of a ring. 

Apparent Diameter — The diameter of a body as seen from 
the earth. 

Apparent Motion — The motion of a body as seen from the 
earth. 

Apparent Time — Time as shown by the sun. 

Arc — A part of the circumference of a circle. 

Argument — A number by which an equation is found. 

Asteroids — Starlike bodies which revolve around the sun be- 
tween Mars and Jupiter. 

Attraction — The power of one body to draw another to- 
wards it. 

Calendar — An almanac. 

Cardinal Points — The North, South, East and West points 
of the horizon. 

Centrifugal Force— The tendency that a moving body has to 
fly off into a straight line. 



PRACTICAL ASTRONOMY. 57 

Centripetal Force — The force which draws a moving body 
towards the centre of motion. 

Degree — One-360th part of the circumference of a circle. 

Digit — One-12th part of the apparent diameter of the sun 
or moon. 

Disc — The apparent surface of a heavenly body. 

Earth — The sphere on which we live. 

Ecliptic — The plane of the earth's orbit. 

Equator — A great circle of the earth, 90 degrees from the 
poles. 

Equinoxes — The points where the sun crosses the Equator. 

Horizon — The circle where the sky and earth appear to meet. 

Limb — The edge of the sun or moon. 

Minute — One-60th part of a degree : also, one-60th part of 
an hour. 

Nadir — The point directly under foot. 

Opaque — Not luminous. 

Radius Vector — A straight line drawn from the revolving 
body to the centre of motion. 

Rotation— The motion of a body round its axis. 

Satellite-A moon, or secondary planet. 

Second — One-60th part of a minute. 

Transit — The passage of a body across the sun's disc. 

Zenith — The point in the heavens directly overhead. 



H 



iistidex:. 



FA UK. 

Preface ,. 3 

The Solar System 5 

The Sun ,... 5 

Mercury.. 7 

Figure!.. ,. 7 

Venus g 

TheEarth p 

Heat Below the Earth's Surface 9 

The Moon j] 

Mars 13 

Jupiter , ]4 

Figure2 1G 

Saturn 17 

Uranus 18 

Neptune 1H 

Representation of the Solar System 19 

Comets gO 

Elements of three Comets 21 

Fixed Stars 22 

Are the Celestial Worlds Inhabited .24 

Practical Astronomy 2? 

Remarks... - 28 

Moon's Phases g<» 

Table 1 30 

Table II 31 

Table III ; 32 

Table IV 33 

Table V , 35 

Equation of Time 37 

Table VI 38 

The Weather 41 

Table VII 42 

To Find the Day of the Week Corresponding to the Day of the Month 43 

Easter 44 

Perigee, Apogee, &c 45 

Table VIII 40 

Eclipses 48 

Table IX, 50 

Catalogue of Solar Eclipses 51 

Kepler's Laws 52 

Tabular View of the Solar System (Table X) ... 53 

Transits of Mercury and Venus 54 

To produce Table I 54 

Vocabulary of Astronomical Terms... 56 






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